[Ifeffit] [Ext] Re: Question about mixed second coordination shell

Thu Jan 18 01:50:05 CST 2024

Dear Robert, Dear Carlo,
Thank you for sharing your knowledge.
I have scheduled beamline time next month, during which I can measure
samples prepared under various conditions; this might prove helpful.
Additionally, I have requested a cryostat for other measurements. I plan to
measure FMN at low temperatures as well, in the hope of detecting some
signal for sodium.
Once again, thank you!
Best regards.

(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)

Eugenio H. OTAL
Assistant Professor
Dept. of Materials Chemistry
Shinshu University
4-17-1 Wakasato, Nagano 380-8553, JAPAN
eugenio_otal at shinshu-u.ac.jp
https://sites.google.com/view/zettsu-laboratory/news-updates

¯\_(ツ)_/¯¯\_(ツ)_/¯

Who is John Galt?

¯\_(ツ)_/¯¯\_(ツ)_/¯

On Thu, Jan 18, 2024 at 6:26 AM Carlo Segre <segre at iit.edu> wrote:

> As Robert notes, it is likely that you have a lot of disorder in the Na
> sites, particularly if there is also a P3 to O3 transition happening.  If
> the second shell fits using just the metal and oxygen atoms are reasonable,
> then I would simply not worry about the Na and make the case that the
> disorder washed out their contribution.  More importantly, I would focus on
> the bond lengths of the atoms you can see to detect a structural transition
> although it will be very difficult as the transition typically consists of
> the layers sliding against one another without changing the bond
> lengths internal to the layers very much.  If you want to discuss this more
> off the list I am happy to do so.
>
> Carlo
>
> On Wed, Jan 17, 2024 at 1:41 AM Otal Eugenio <eugenio_otal at shinshu-u.ac.jp>
> wrote:
>
>> Dear Carlo,
>> Thanks for your answer.
>> Yes, it is a layered material. I was measuring in situ the transformation
>> from O3 to P3.
>> I am not sure that Na atoms are ordered, it is a light element in a
>> layered structure and I applied some cycles to form the electrolyte-cathode
>> interphase, and disorder can be found there. I shook the structure a
>> little, your observation is correct.
>> I compared the spectra of a non-cycled one (blue) with a cycled one (red)
>> and the differences are minimal.
>> [image: image.png][image: image.png]
>> I was measuring all the edges, all showed the same problem, Na is
>> impossible to include in the fitting.
>> The goal was to monitor changes in the first coordination shell during
>> the battery operation. I found all the necessary information to understand
>> the system.
>> To fit the second coordination shell was attempted to evaluate the Na
>> concentration along the cycles and complement the electrochemical
>> measurements.
>> Best regards.
>>
>>
>>
>>
>> (^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
>>
>> Eugenio H. OTAL
>> Assistant Professor
>> Dept. of Materials Chemistry
>> Shinshu University
>> 4-17-1 Wakasato, Nagano 380-8553, JAPAN
>> eugenio_otal at shinshu-u.ac.jp
>> https://sites.google.com/view/zettsu-laboratory/news-updates
>>
>> ¯\_(ツ)_/¯¯\_(ツ)_/¯
>>
>> Who is John Galt?
>>
>> ¯\_(ツ)_/¯¯\_(ツ)_/¯
>>
>>
>>
>> On Wed, Jan 17, 2024 at 2:56 PM Carlo Segre <segre at iit.edu> wrote:
>>
>>> Hi Eugenio:
>>>
>>> This looks like a layered structure, most likely a P2 or P3 phase.  Is
>>> this correct?  How sure are you that you have a single phase and that the
>>> Na ions are well ordered?  Is it possible that there is so much disorder in
>>> the M-Na distances that they wash out any contribution?  In that case, the
>>> second M-O distance would probably be more important.  You also do not
>>> mention if this is Ni, Fe or Mn edge data.  Is it possible that these
>>> differ?
>>>
>>> Carlo
>>>
>>>
>>>
>>> On Tue, Jan 16, 2024 at 11:30 PM Otal Eugenio <
>>> eugenio_otal at shinshu-u.ac.jp> wrote:
>>>
>>>> Dear Robert,
>>>> Thanks for your detailed answer.
>>>> I am cutting at R=3.35. I also tried to go up to 4.0 to provide more
>>>> freedom and to include the SS TM-O at 3.6.
>>>> It seems that including MS was not fruitful at the moment. I found the
>>>> contribution very tiny, Importance < 10.
>>>> I included the path at 3.6, and it fits well, but when I include the
>>>> Na, the CN_Na goes to high values (>10) and errors (~+/- 50)
>>>> I also tried to restrict the CN of TM to force the Na to take place and
>>>> get good results. Also useless.
>>>> I was checking the data in R_real and the TM and Na paths. I see the TM
>>>> path is in phase while the Na path is not. I wonder if this is affecting
>>>> the fit. How should I constrain the fitting to solve this situation?
>>>> Best regards.
>>>>
>>>> [image: image.png]
>>>>
>>>>
>>>>
>>>> (^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
>>>>
>>>> Eugenio H. OTAL
>>>> Assistant Professor
>>>> Dept. of Materials Chemistry
>>>> Shinshu University
>>>> 4-17-1 Wakasato, Nagano 380-8553, JAPAN
>>>> eugenio_otal at shinshu-u.ac.jp
>>>> https://sites.google.com/view/zettsu-laboratory/news-updates
>>>>
>>>> ¯\_(ツ)_/¯¯\_(ツ)_/¯
>>>>
>>>> Who is John Galt?
>>>>
>>>> ¯\_(ツ)_/¯¯\_(ツ)_/¯
>>>>
>>>>
>>>>
>>>> On Wed, Jan 17, 2024 at 1:24 AM Robert Gordon <ragordon at alumni.sfu.ca>
>>>> wrote:
>>>>
>>>>> Hi Otal,
>>>>>
>>>>> I ran a quick FEFF simulation just to see what is present under that
>>>>> second peak in the FT.
>>>>> There are many more shells than just TM and Na...e.g.
>>>>>
>>>>>
>>>>> There is significant multiple scattering and another backscattering
>>>>> peak (Fe-O) at
>>>>> 3.6Angstroms. All of these are going to spread underneath that peak in
>>>>> the FT. You might
>>>>> also be getting some interference from the 4.07A MS stuff. It doesn't
>>>>> seem a surprise that
>>>>> just including TM and Na is giving problems.
>>>>>
>>>>> What is your high-R cutoff? Have you tried including
>>>>> multiple-scattering or that 4th backscattering
>>>>> contribution?
>>>>>
>>>>> cheers,
>>>>> Robert
>>>>>
>>>>> On 2024-01-09 12:06 a.m., Otal Eugenio wrote:
>>>>>
>>>>> Dear all,
>>>>> Happy New Year!
>>>>> I am dealing with the fitting of NaMn0.3Fe0.4Ni0.3O2 second shell.
>>>>> I have Mn, Ni, and Fe at 2.9772Å and Na at 3.1859Å, showing only one
>>>>> shell. If I use any of the transition metals (dZ <5) for fitting the second
>>>>> coordination shell. fitting is fine, but when I introduce the Na path, the
>>>>> fitting has no sense, CN_Na grows and also its error.
>>>>> Even including Na, I have Nvary = 10 and Ninp = 13.98, so I am getting
>>>>> out of ideas and nothing helpful in the ifeffit Archive until now.
>>>>> Is there any strategy for dealing with mixed second coordination
>>>>> shells? I am attaching the file exported from Larch and the cif file.
>>>>> Best regards.
>>>>>
>>>>>
>>>>> (^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
>>>>>
>>>>> Eugenio H. OTAL
>>>>> Assistant Professor
>>>>> Dept. of Materials Chemistry
>>>>> Shinshu University
>>>>> 4-17-1 Wakasato, Nagano 380-8553, JAPAN
>>>>> eugenio_otal at shinshu-u.ac.jp
>>>>> https://sites.google.com/view/zettsu-laboratory/news-updates
>>>>>
>>>>> ¯\_(ツ)_/¯¯\_(ツ)_/¯
>>>>>
>>>>> Who is John Galt?
>>>>>
>>>>> ¯\_(ツ)_/¯¯\_(ツ)_/¯
>>>>>
>>>>>
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>>>
>>>
>>> --
>>> Carlo U. Segre (he/him) -- Duchossois Leadership Professor of Physics
>>> Professor of Materials Science & Engineering
>>> Director, Center for Synchrotron Radiation Research and Instrumentation
>>> Illinois Institute of Technology
>>> Phone: 312.567.3498
>>> segre at iit.edu   http://phys.iit.edu/~segre   segre at debian.org
>>>
>>> _______________________________________________
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>
>
> --
> Carlo U. Segre (he/him) -- Duchossois Leadership Professor of Physics
> Professor of Materials Science & Engineering
> Director, Center for Synchrotron Radiation Research and Instrumentation
> Illinois Institute of Technology
> Phone: 312.567.3498
> segre at iit.edu   http://phys.iit.edu/~segre   segre at debian.org
>
>
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